For various objects-to-be-dehumidified including outdoor or indoor electronic enclosures such as lights, such as street lamps and vehicle lamps, distribution boards, communication equipment, security equipment, and photovoltaic systems, moisture needs to be removed from the enclosures to protect internal circuits or elements.
Specifically, it is ideal to apply a sealing structure for waterproofing to an electronic enclosure such as a control panel or a distribution board, particularly an electronic enclosure installed outdoors. However, as the air inside the enclosure shrinks and expands according to change in temperature inside and outside the electronic enclosure, a vent for pressure balance is commonly introduced in order to prevent breakage of various components, elements, etc. in the electronic enclosure due to internal pressure fluctuation.
When the vent is employed, air can flow through the electronic enclosure, and thus there is a possibility of moisture condensation in the enclosure due to the temperature difference.
For example, a vehicle lamp, which can be classified as an electronic enclosure, has an open structure for ventilation, not an airtight structure, in order to relieve the internal pressure of air that is expanded along with rise of the internal temperature at the time of lighting. Accordingly, condensation often occurs due to differences in temperature and humidity between the inside and outside of the lamp.
If the condensation inside the lamp is repeated and the condensation state is not addressed, problems may arise in the original properties (emission angle, etc.) of the lamp, which may adversely affect safety and deteriorate electric insulation, thereby encountering other problems.
To address this problem, a vehicle head lamp having a moisture removing means is disclosed in Korean Patent Application Publication No. 10-2006-0067597 (published on Jun. 20, 2006).
This patent document discloses a vehicle head lamp having a moisture removing means for removing moisture formed on the inner surface of a head lamp lens cover installed on the front surface of the head lamp when the head lamps inserted into the head lamp housings on both left and right sides of the vehicle operate.
Specifically, the vehicle head lamp includes a moisture removing means installed in a moisture production area where moisture is produced during operation of the head lamp inside a head lamp lens cover installed on a front surface of the head lamp and formed in a round shape to have a height difference at both ends thereof; and an overheat prevention unit capable of cutting off the current when the current flowing during operation of the moisture removing unit is excessive.
However, the moisture removing means, which is provided with a heater of a hot wire, is insufficient to effectively discharge air from the lamp and is less practical in that it raises a safety issue when it is operated at a temperature higher than the temperature at the time of lamp lighting.
Korean Patent Application Publication No. 10-2012-0050268 (published on May 18, 2012) also discloses a dehumidification method of a vehicle head lamp.
According to this patent document, the method includes a diffuse reflection measurement step of measuring diffuse reflection of a light source emitted from a light through a photodiode sensor mounted on a head lamp of a vehicle; a diffuse reflection comparison/determination step of comparing a diffuse reflection result value measured in the diffuse reflection measurement step with an initially set reference value; a power driving step of driving power through a controller operatively connected with an ECU provided in the vehicle when the diffuse reflection result value measured in the diffuse reflection comparison/determination step exceeds the reference value; and a dehumidification step of dehumidifying the inside of the head lamp by operating a fan operatively connected with the controller during power driving in the power driving step.
However, it is considered to be difficult in reality to implement a dehumidification technique by operating only the fan in the vehicle lamp that has a constant ventilation structure.
Next, Korean Patent No. 10-1366848 (registered on Feb. 14, 2014) discloses a moisture removing apparatus for an automotive head lamp.
This patent document discloses a head lamp dehumidifying apparatus installed in a head lamp housing of an automobile to circulate air inside a head lamp to remove moisture. The head lamp dehumidifying apparatus includes a ventilation unit for preventing inflow of water droplets from the outside and discharging moisture and hot gas to the outside, the ventilation unit being installed in a discharge hole to discharge internal air from a lamp housing, a moisture absorption unit for absorbing or adsorbing moisture contained in the air inside the head lamp, and an air blowing unit for forcibly circulating the air in the head lamp.
However, this patent is also less practical as it fails to propose a solution to the problem that the moisture absorption unit catches not only the moisture inside the lamp but also the outside moisture due to the nature of the lamp structure of the vehicle, which has a constant ventilation structure.
Another conventional technology is disclosed in Korean Patent No. 10-0836307 (“DEHUMIDIFICATION STRUCTURE OF HEAD LAMP FOR VEHICLE USING BENTONITE NATURAL CLAY PACK”) (registered on Jun. 2, 2008).
This patent relates to a dehumidification structure of a head lamp for a vehicle using a bentonite natural clay pack.
In particular, the bentonite natural clay pack is used as a desiccant to absorb water at a temperature below 50° C., and to evaporate water at 50° C. to 100° C., thereby enabling dehumidification of the head lamp.
More specifically, the dehumidification structure of a head lamp for a vehicle includes a bentonite natural clay pack configured to absorb moisture at a temperature below a predetermined temperature range and evaporate moisture at a predetermined temperature range, the bentonite natural clay pack having a regenerative capacity through repetition of absorption and evaporation, a bentonite natural clay pack accommodating space for accommodating the bentonite natural clay pack, provided in a lower portion of the side surface of a head lamp bezel near a head lamp bulb, and a fixing bracket for fixing the bentonite natural clay pack to the head lamp bezel.
However, this patent only provides a dehumidification member composed of a bentonite natural clay pack and fails to provide a solution to the problem occurring in absorbing moisture contained in the external air circulating inside the same lamp as the above two conventional technologies.